Area type photo-electric control device



July 20, 1965 D. A. BAKER AREA TYPE PHOTO-ELECTRIC CONTROL DEVICE FiledSept. 12, 1961 2 Sheets-Sheet 1 July 20, 1965 Filed Sept.

D. A. BAKER AREA TYPE PHOTO-ELECTRIC CONTROL DEVICE 2 Sheets-Sheet 2United States Patent 3,196,278 AREA TYPE PHDTQ-ELECTRIC (IONTROL DEVICEDale A. Baker, Waukesha, Wis, assignor to Cutler- Hammer, Inc,Milwaukee, Wis, a corporation of Delaware Filed Sept. 12, 1961, Ser. No.137,653 12 Claims. (1. 258-437) This invention relates to a controldevice for a regulator and particularly to a position-to-voltage typetransducer with an output voltage suitable for use as a reference signalfor a regulator.

Photo-electric type devices have been used previously to produce areference signal for a regulator in response to variations in theintensity of light on the photo-electric cells. mination on the interiorsurface of a concentrically located sphere. Any surface which does notconsist of a portion of such a concentrically located sphere will beunevenly illuminated by a point light source. Any mechanical devicewhich modulates the light emanating from a point source and falling upona plane surface must be compensated for this uneven illumination. Incontrast a true area light source will cause uniform illumination of aplane of the same size as the area light source if such plane is locatedparallel to the area light source and with the spacing between thereceiving plane and the area light source small with respect to thesmall est dimension of the receiving plane.

A general object of the invention is to provide an improvedphoto-electric type of control device which affords a controllableoutput signal.

The primary object of this invention is to provide a simple electronicdevice for controlling the speed of an electric motor in response to theposition of a master control.

A further object of this invention is to provide irnproved meansaffording an electric motor speed control reference signal that is pureDC.

Other objects and advantages will be pointed out in or be apparent fromthe specification and claims, as will obvious modifications of theembodiments shown in the drawings, in which:

FIGURE 1 is a side view of a first embodiment of the control device;

FIG. 2 is a bottom view of the control device of FIG. 1;

FIG. 3 is a bottom view of a modified type shade for the control deviceof FIGS. 1 and 2;

FIG. 4 is a bottom view of another modification of the shade for thecontrol device of FIGS. 1 and 2;

FIG. 5 is a side View of a second embodiment of the control devicewherein the output voltage is controlled by adjustment of the supplyvoltage;

FIG. 6 is a side view of a third embodiment of the control devicewherein the output voltage is controlled by adjustment of the supplyfrequency; and

FIG. 7 is a side view of a modification of the control device of FIG. 6wherein the light is filtered.

Referring to the drawings, the control device is shown in FIGS. 1 to 4generally as including an area type primary light source 10, such as anelectroluminescent panel, connected to an AC. source of power L L A pairof area type photo-electric cells 12 and 14, such as self-generatingselenium cells, of equal size are positioned above the light sourceparallel and very close to the light source and in a light-tightenclosure (shown in broken lines in FIG. 1). The area of the panel forthe light source is shown as being slightly greater than the combinedareas of the photo-electric cells so that the light intensity will beassured of being equal over the A point light source will produceuniform illuentire surface of the photo-electric cells. The cells areindependently connected to the motor regulator by respective pairs ofconductor 15, 17 and 19, 21 to provide pure D.C. voltages to control thespeed of the motor. The motor regulator can be constructed so that therotation of the motor depends upon which cell is exposed to the sourceof light and this can obviously be coordinated with the direction ofmotion of the handle.

An arcuate opaque shade 16 is secured to the end of a control rod 18pivoted at 20 and is movable between the light source and thephoto-electric cells upon movement of the control rod. Since the outputfrom the light source is constant and the voltage output of the cells isdirectly proportional to the intensity of light on their surfaces or theamount of such surface exposed to light of constant intensity the shadeis cut to expose an increasing amount of surface of one cell or theother to the light as the shade is rotated to the right or left. Theincrease in light applied on the cell will produce a low power pure DC.voltage that increases in a manner directly related to the contour ofthe shade. In FIG. 3 the shade is designed to provide a dead band whenthe control rod is initially rotated in either direction with a slowlyincreasing light exposure whi le the shade in FIG. 4 allows a smallamount of light to reach the cells when the control rod is at neutraland increases the light exposure rapidly. It should be apparent that thesame result could be accomplished by either contouring the light sourceor the cells to change the characteristic of the output of the cells.

In a practicalapplication of this device, such as in a crane, the lightsource is connected across power supply lines L and L and the photocellsare connected to control the speed and direction of rotation of thecrane lift motor. Since the DC. voltage output of the cells willincrease as the total amount of light on the cells increases, thefarther the shade is rotated in either direction the larger will be thereference signal to the regulator which can cause the motor to runfaster. It can be seen that as the control rod is rotated clockwise(FIG. 1), cell 14 will be exposed to the light. The farther the rod isrotated, the greater the area of exposure. The position of the rod,therefore, determines the output of the photocells and this output isused to control both the direction of rotation and speed of the motor.The intensity of the light source is determined by the AC. voltage whichcan be varied with respect to a second parameter if desired. Somephosphors used in electroluminescent light sources will produce a lightthe wave length of which is somewhat dependent upon the frequency of theapplied A.C. voltage. Therefore, the use of colored filters between theelectroluminescent panel and the photocells can make the output of thephotocells somewhat dependent upon the frequency of the AC. voltageapplied to the electroluminescent light source which may then be made afunction of a third parameter.

In FIGS. 5, 6 and 7, reference characters like those in FIG. 1 have beenemployed for like elements. The embodiment in FIG. 5 differs from thatin FIG. 1 in that the shade has been omitted. Also, a voltage adjuster22 is connected in power supply lines L and L or to the power supplysource to enable adjustment of the magnitude of the alternating voltageapplied to light source 10. Increase or decrease in the voltagemagnitude respectively increases or decreases the intensity of the lightemitting from source til. The embodiment in FIG. 6 diifers from that inFIG. 5 in that a frequency adjuster 23 is used in place of the voltagemagnitude adjuster. Increase or decrease in the supply frequencyrespectively increases or decreases the intensity of the light emittedfrom source 10. The modification in FIG. 7 differs from FIG, 6 in that acolored filter 24 has been mounted between light source 10 andphoto-cells 12 and 14. Since the wave length of the light i dependent onthe frequency of the alternating current source L -L filter 24 may beemployed to block all or part of the light at one source frequency andto vary the passage of light therethrough as the frequency is adjusted.

A significant feature provided by this system is that the output voltageproduced by the photo-electric cells is a pure DC. voltage which doesnot require filtering before use as a reference signal in a fastresponse regulator. This transducer also has neither the counter-torquetype of force feedback such as produced by the magnetic type transducernor a friction type force feedback such as produced by a potentiometertype transducer.

Although several embodiments of the present invention have beenillustrated and described, it Will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the scope of the appended claims.

I claim:

1. A selectively adjustable control device for providing an electricalsignal having a magnitude which is proportional to adjustment of thecontrol device comprising:

area-type photo-electric means responsive to variable light to provide aproportionally variable electrical output signal;

an area-type primary luminescent source spaced closely parallel to saidphoto-electric means so that unit areas of said photo-electric means areexposed to light emitted from corresponding unit areas of saidluminescent source;

and means for continuously adjusting the amount of 7 light impinging onsaid photo-electric means directly from said luminescent sourceproportionally to adjust the magnitude of said output signal. 2. Theinvention defined in claim 1, wherein said means for continuouslyadjusting the amount of light impinging on said photo-electric meansfrom said luminescent source comprises:

an opaque shade positioned in the small space between said luminescentsource and said photo-electric means; and means for steplessly movingsaid shade to adjust the area of said photo-electric means that isexposed to light from said luminescent source. 3. The invention definedin claim 1, wherein said primary luminescent source comprises:

an electro-luminescent member; and an alternating current power supplysource connected to said member to cause light emission therefrom;

and said means for continuously adjusting the amount of light-impingingon said photo-electric means from said luminescent source comprisesmeans for adjusting the magnitude of voltage applied to saidelectroluminescent member thereby proportionally to adjust the intensityof light emitted therefrom onto said photo-electric means.

4. The invention defined in claim 1, wherein said primary luminescentsource comprises:

an electro-luminescent member; and anjalternating current power supplysource connected to said member to cause light emission therefrom; andsaid means for continuously adjusting the amount of light impinging onsaid photo-electric means from I said luminescent source comprises meansfor adjusting the frequency. of the voltage applied to saidelectro-luminescent member thereby proportionately to adjust theintensity of light emitted therefrom onto 7 said photo-electric means.

p 5. The invention defined in claim 4, together with:

a stationary colored filter between said electro-luminescent member andsaid photo-electric means for passa 7 ing light therethrough as afunction of the Wavelength of such light.

6. An adjustable control device for providing an electrical signalhaving a magnitude which is proportional to adjusted position of thecontrol device comprising:

area-type photo-electric means responsive to variable light to provide aproportionally variable electrical output signal;

area-type luminescent source means spaced closely parallel to saidphoto-electric means so that portions of said photo-electric means areexposed to light emitted from corresponding portions of said luminescentsource means;

area-type opaque shade means mounted for lateral step less movement inthe small space between'said lumi: nescent source means and saidphoto-electric means;

and one of said means being provided with a configuration which operatesin conjunction with movement of said shade to cause the magnitude ofsaid output signal to change proportional to such movement.

7. The invention defined in claim 6, together with:

an opaque housing completely enclosing said photoelectric means and saidluminescent source means and said shade means;

and control means extending from the exterior of said housingtherewithin for moving said shade means.

8. The invention defined in claim 6, wherein said one of said means isprovided with a configuration Which comprises a straight edge so thatuniform incremental movements of said shade means cause respectivedirectly and linearly proportional changes in the magnitude of saidoutput signal.

, 9. The invention defined in claim 6, wherein said one of said means isprovided with a configuration which corn: prises an edge ofprogressively increasing curvature so that uniform incremental movementsof said shade means cause successively larger increments in themagnitude of said output signal.

' 10. The invention defined in claim 6, wherein said one of said meansis provided with a configuration which comprises an edge ofprogressively decreasing curvature so that uniform incremental movementsof said shade means cause successively smaller increments in themagnitude of said output'signal. i 11. An adjustable control device forproviding a direct current electrical signal having a'magnitude which isproportional to adjustment of said control device comprising:

a planar photo-electric element responsive to variable light to'providea direct current signal having a proportionally variable magnitude;

a planar .electro-luminescent member having an area at least as large asthe area of said photo-electric element and having its light emittingsurface spaced closely parallel to the light responsive surface or" saidphoto-electric element so that unit areas of the latter are in directlight exposure relation with corresponding unit areas of saidelectro-luminescent member;

an opaque shade;

' means mounting said opaque shade for movement in the small spacebetween said electro-lurninescent member and said photo-electricelement;

an opaque enclosure for the aforementioned parts to prevent other lightfrom impinging on said photoelectric element;

means on the exterior of said enclosure and extending into the latterfor afiording continuousmovement of said shade to adjust the amount oflight passing from said electro-luminescent member directly onto saidphoto-electricelement;

and an alternating current power supply source and conductors extendingtherefrom into said enclosure and being connected to saidelectro-luminescent member for energizing the latter with an alternatingcurrent field.

12. A selectively adjustable control device for provid-- ing a selectedone of a plurality of electrical signals and a magnitude therefor whichare functions of the adjustment of said control device comprising:

a plurality of area-type photo-electric elements arranged inside-by-side relation, each said element being responsive to variablelight exposure to provide a proportionally variable output signal andhaving a pair of terminals for connecting the same to a device to becontrolled;

an area-type luminescent source having an area at least as large as thecombined areas of said photo-electric elements and having its lightemitting surface spaced closely parallel to the light responsivesurfaces of said photo-electric elements;

an opaque shade mounted for continuous lateral movement in the smallspace between said luminescent source and said photo-electric elements;

and said shade being provided with a configuration comprising aplurality of cutout portions whereby movement thereof in a selecteddirection causes exposure of an increasing amount of surface of aselected photo-electric element to said luminescent source.

References Cited by the Examiner UNITED STATES PATENTS 2,030,854 2/36Calver 250-229 X 2,740,901 4/56 Graham 250-212 X 2,753,487 7/56 Bone250-229 X 2,780,731 2/57 Miller 250-213 2,858,449 10/58 Burr 250-105 X2,879,405 3/59 Pankove 250-211 2,896,086 7/59 Wunderman 250-2112,904,697 9/59 Halsted 250-213 3,015,731 1/62 Van Santen et a1 250-2133,033,073 5/62 Shuttleworth 250-211 3,046,540 7/62 Litz et a1. 250-2133,093,741 6/63 Meyer 250-212 3,121,795 2/64 Marvin 250-212 3,134,9075/64 Volberg 250-237 FOREIGN PATENTS 223,728 7/59 Australia.

RALPH G. NILSON, Primary Examiner.

ARCHIE R. BORCHELT, Examiner.

1. A SELECTIVELY ADJUSTABLE CONTROL DEVICE FOR PROVIDING AN ELECTRICALSIGNAL HAVING A MAGNITUDE WHICH IS PROPORTIONAL TO ADJUSTMENT OF THECONTROL DEVICE COMPRISING: AREA-TYPE PHOTO-ELECTRIC MEANS RESPONSIVE TOVARIABLE LIGHT TO PROVIDE A PROPORTIONALLY VARIABLE ELECTRICAL OUTPUTSIGNAL; AN AREA-TYPE PRIMARY LUMINESCENT SOURCE SPACED CLOSELY PARALLELTO SAID PHOTO-ELECTRIC MEANS SO THAT UNIT AREAS OF SAID PHOTO-ELECTRICMEANS ARE EXPOSED TO